Rhythmic exocytosis stimulated by GnRH-induced calcium oscillations in rat gonadotropes.
Science
; 260(5104): 82-4, 1993 Apr 02.
Article
en En
| MEDLINE
| ID: mdl-8385366
ABSTRACT
In pituitary gonadotropes, gonadotropin-releasing hormone (GnRH) induces the rhythmic release of Ca2+ from an inositol 1,4,5-trisphosphate (IP3)-sensitive store. Simultaneous measurement of the concentration of cytosolic free Ca2+ ([Ca2+]i) and exocytosis in single identified gonadotropes showed that each elevation of [Ca2+]i induced a burst of exocytosis. These phenomena were largely suppressed by buffering of [Ca2+]i but persisted in the absence of extracellular Ca2+. Activation of voltage-gated Ca2+ channels by brief depolarizations seldom supplied enough Ca2+ for exocytosis, but [Ca2+]i elevations induced by photolysis of caged IP3 did trigger exocytosis, confirming that GnRH-stimulated gonadotropic hormone secretion is closely coupled to intracellular Ca2+ release. Agonist-induced oscillations of [Ca2+]i in secretory cells may be a mechanism to optimize the secretory output while avoiding the toxic effects of sustained elevation of [Ca2+]i.
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Banco de datos:
MEDLINE
Asunto principal:
Hipófisis
/
Calcio
/
Hormona Liberadora de Gonadotropina
/
Exocitosis
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Science
Año:
1993
Tipo del documento:
Article